1. Field of the Invention
The invention regards a progressive vortex pump used in pumping systems, such as oil wells.
2. Description of the Related Art
A conventional progressive vortex pump was described in US2008050249. This progressive vortex pump comprises a pumping assembly provided with an inlet housing in contact with the fluid to be pumped and an outlet housing connected to a pumping pipe. The pump assembly is driven by a shaft connected to a motor assembly.
When the progressive vortex pump is installed in a well, such as an oil well, the pumping assembly is positioned within a well casing pipe, which has its upper end located at the well surface and lower end in contact with the fluid to be pumped. Similarly, the pumping pipe extends inside the well casing pipe up to the surface of the well.
In US2008050249, the shaft of the progressive vortex pump extends from the pumping assembly through the pumping pipe to the motor assembly located at the well surface. BRMU8802106-8 describes a progressive vortex pump, wherein the shaft extends from the pumping assembly up to a motor assembly comprising a submerged electric motor positioned below said pumping assembly.
Both in the progressive vortex pump with surface motor assembly, and in the progressive vortex pump with submerged motor assembly, the pumping assembly is further provided with a pump housing, inside of which multiple adjacent pumping stages are arranged, each pumping stage comprising a stator attached within the pump housing, a primary diffuser coupled to the anterior side of the stator, a second diffuser coupled to the posterior side of the stator, and a disc-shaped rotor having a central bore and a rim with vanes, said rotor being coupled to the shaft and positioned internally to the stator.
As disclosed in US2008050249, each pumping stage comprises a stage inlet connected with a circular channel, which is connected with a stage outlet. The rotor vanes are arranged inside the circular channel. The pumping stages are arranged in such a way that the stage outlet of an anterior pumping stage is connected with the stage inlet of a posterior pumping stage.
US2015330392 discloses a progressive vortex pump which is different from the pump disclosed in US2008050249 by the fact that each pumping stage comprises at least two stage inlets, each stage inlet being connected with a respective circular channel, each circular channel being connected with a respective stage outlet, said stage inlets are evenly distributed along the stator internal perimeter, said stage outlets are evenly distributed along the stator internal perimeter, and said pumping stages being arranged in such a way that each stage outlet of an anterior pumping stage is connected to a respective stage inlet of a posterior pumping stage. This setting solved the problem of excessive shear stress on the pump shaft.
Both in the US2008050249 pump, as in the US2015330392 pump, under operating conditions, when the rotor spins, the fluid enters the pumping stage through at least one stage inlet, passes through the respective circular channel and exits the pumping stage through the respective stage outlet, being forwarded to the next pumping stage. Thus, fluid pressure increases between the stage inlet and the respective stage outlet, and it also increases from one pumping stage to the next, along the pumping direction.
Under operating conditions, besides pumping the fluid through at least one stage inlet, passing through the respective circular channel and exiting through the respective stage outlet, a film of anterior fluid is formed between the anterior side of each rotor and the posterior surface of the diffuser coupled to the anterior side of the stator, and a film of posterior fluid is formed between the posterior side of each rotor and the anterior surface of the diffuser coupled to the posterior side of the stator.
Since the fluid pressure increases along the pumping direction, the pressure of the posterior fluid film becomes larger than the pressure of the anterior fluid film, exerting an axial load on each rotor, which causes undue rubbing of the rotor against the diffuser coupled to the anterior side of the stator.